Device For Heat-Welding Superposed Flaps Of A Wrapping Enveloping A Set Of Articles

ABSTRACT

The device ( 1 ) is associated, in line, to an outlet of a packing machine and is designed to seal superposed flaps (Ls, Li) of packs (C), at longitudinal vertical sides (V) thereof. The device includes apparatus ( 2 ) for receiving and moving the packs (C) and includes two batteries ( 3, 4 ) of heat-welding rollers ( 30, 40 ), having a vertical axis, for acting on respective longitudinal vertical sides (V) in order to heat the flaps (Ls, Li) up to a temperature which is sufficient to cause joining by aggregation of the packing material. Cooling is provided downstream of the batteries ( 3, 4 ) for acting on the flaps (Ls, Li) in order to lower the temperature thereof and thus stabilize the joint.

TECHNICAL FIELD

The present invention relates to the technical sector of automatic machines for packing a group of articles, ordered in a predetermined scheme, in a protective wrapper of heat-weldable plastic material. In more detail, the invention relates to a device for heat-welding superposed flaps that are located in the two longitudinal flaps of the wrapper, i.e. those which determine the final sealing thereof.

In the prior art for these wrappers there are, for example, those which wrap paper rolls (kitchen rolls, toilet paper, absorbent paper etc.) arranged flanked in one or more superpose layers.

BACKGROUND ART

The above machines, known also as packing machines, in a first constructional design comprise a conveyor line provided with a lower opening, through which the group of articles is first introduced via a vertical movement from the bottom upwards, during which a sheet of plastic material arranged horizontally” is intercepted, which sheet is caused to partially envelop the group; in a following horizontal movement of the group of articles and the associated sheet, insertion in the conveyor line is completed and, due to the action of appropriate lower folding devices, the longitudinal winding of the sheet is also completed, the ends of which sheet end up superposed on the lower horizontal surface of the package.

Heat-welding means are then commanded in phase relation to stably join the transversal edges.

Also known are packing machines in which the group of articles, already ordered and retained by lateral and upper elements, is first introduced to the conveyor line.

The group of articles advances and intercepts a vertical sheet of the plastic material which is induced to wrap the group of articles in a longitudinal direction and, in a following station, is heat-welded at transversal edges of the sheet which are superposed in the rear part of the pack.

In both above-described configurations of the machines, once the longitudinal wrapping of the sheet and the heat-welding of the transversal edges has been completed, the pack is advanced on the conveyor line where it intercepts fixed folder devices which, in successive actions, act on the portions of sheet projecting from the longitudinal vertical sides V of the pack C in order to form, in each of the sides V, in order: a lower flap Li, folded upwards, and an upper flap Ls, folded downwards and partially superposed on the first flap at a strip S having a horizontal development (see FIG. 1).

A device is associated in-line to the outlet of the packing machine, which device receives the package C, keeping the flaps Ls, Li in position folded at the longitudinal vertical sides V, and heat-welds the flaps Ls, Li.

A type of device, of known type and widely used, is schematically illustrated in plan view in FIG. 2 and is constituted by a pair of conveyor belts N, symmetrically arranged such that the respective active branches Ra adhere to the longitudinal vertical sides V of the pack C, thus guaranteeing both the advancement thereof and the retaining of the folded flaps Ls, Li.

Respective rows of heated plates Pc are located internally of the active branches Ra, which plates Pc are sprung in a transversal direction to the advancement of the pack C, and against which the corresponding conveyor belts N drag.

The plates Pc, which can be for example made of aluminum, are heated by electric resistances and maintained at temperatures comprised between 250° and 330°, while the belts N are made preferably of Teflon and are slim, such as to have a low coefficient of friction with the plates Pc and guarantee effective transmission of the heat to the flaps Ls, Li which, retained between the belts N, are progressively brought to the melting temperature and joined by aggregation of the material.

Cold plates Pf are also located internally of the active branches Ra, following the rows of hot plates Pc, which cold plates Pf are also preferably sprung and are destined to lower the temperature of the flaps Ls, Li, in order to solidify the material and thus stabilize the completed welding.

The main drawback with a device made in this way is that the Teflon conveyor belts N suffer high degrees of wear and, due to the dragging against the plates, both hot and cold, have to be replaced frequently, about every seven to ten days of work, with heavy costs due to the cost of replacement, the intervention of operatives and machine down-time.

Adding to the problem of wear on the belts N, there is also the fact that the conveyor system of the most widely-used packing machines, due to the conformation thereof, impresses on the pack C during the final tract in which the pack is released to enter the device, a transitory acceleration which causes dragging on the initial tract of the belts N.

SUMMARY OF THE INVENTION

The aim of the present invention is to provide a device for heat-welding superposed flaps in a pack wrapping a group of articles, which device is conformed such as to obviate the drawbacks of the known devices.

A further aim of the invention relates to the intention to provide a universal device, i.e. able to interface with all types of packing machines without any need for modifications.

A still further aim of the invention is to provide a device which is conformed in such a way as to absorb, with no negative consequences, any phenomenon of transitory acceleration impressed on the packs by the conveyor system of the packing machine.

A further aim of the invention consists in providing an especially reliable device as regards functioning, which can provide optimal heat-welding of the flaps, while at the same time being of simple conception, such that production costs are limited.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristics of the invention will emerge from the following description of a preferred embodiment of the device, in agreement with what is set out in the claims and with the aid of the accompanying figures of the drawings, in which:

FIG. 1 is a perspective view of a pack of paper rolls, with the flaps to be heat-welded in evidence;

FIG. 2 is a schematic plan view of a device for heat-welding flaps of known type, cited in the preamble hereto;

FIG. 3 is a schematic plan view of the device for heat-welding the flaps of the invention;

FIG. 4 is a lateral view of the device of FIG. 3, sectioned along plane IV-IV of FIG. 3;

FIG. 5 is a transversal cross-section of the device, along plane V-V of FIG. 4;

FIG. 6 is an enlarged-scale illustration of a part of FIG. 3 with the relative means in operating condition;

FIG. 7 is a still-further enlarged-scale illustration of detail K1 of FIG. 6, which highlights some constructional and operative details;

FIG. 8 is a similar view to that of FIG. 6, showing a constructional variant of the device;

FIG. 9A is a still-further enlarged view of detail K2 of FIG. 2, illustrating a first constructional solution relating to heat-welding rollers;

FIG. 9B, similarly to FIG. 9A, illustrates a second constructional solution relating to heat-welding rollers;

FIG. 10 is an axial section, along plane X-X, of the heat-welding roller of FIG. 9B.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to the figures of the drawings, 1 denotes in its entirety the device for heat-welding of the invention, in an overall view.

The device 1 is destined to be associated, in line, downstream of a packing machine of known type, not illustrated in detail but of which the terminal portion of the conveyor line T can be viewed in the figures.

As already described herein above, the packing machine is designed to pack a group of articles, for example rolls of paper towels, toilet paper, absorbent paper and the like, which are ordered in a predetermined fashioned in a protective wrapper made of a heat-weldable plastic material, for example polythene.

The pack C which obtains at the exit of the conveyor line T exhibits, at each of the two longitudinal vertical side V thereof, of which only one is visible in FIG. 1, a lower flap Li, folded in an upwards direction, and an upper flap Ls, folded in a downwards direction and partially superposed on the lower flap Li, at a strip S having a horizontal development.

The device 1, similarly to the known-type device illustrated in FIG. 2 and cited in the preamble hereto, is destined to receive the pack C, keeping the flaps Ls, Li in position, folded at the longitudinal vertical sides V, and to heat- weld the flaps Ls, Li .

The device 1 comprises means 2 for receiving the packs C, and for moving the packs C downstream of the conveyor line T, in the same direction and at a velocity which is at least equal to the velocity of the line T.

The means 2, in the preferred embodiment of the device 1 of FIGS. 3, 4, 5, 6, comprise an inlet group 10, constituted by a pair of conveyor belts 11, 12, arranged symmetrically and provided for intercepting the longitudinal vertical sides V of the pack C, in outlet from the conveyor line T.

Each of the belts 11, 12 is closed ring-wound and stretched between corresponding pairs of pulleys, respectively a drive pulley 110, 120 and a driven pulley 111, 121, having relative vertical axes.

The belts 11, 12 are made of a very sturdy material, for example a textile or a rubbery material having metal wire inserts, and are able to provide a good friction coefficient in the contact surface with the vertical sides V of the pack C.

The drive pulleys 110, 120 are keyed on respective shafts with interposing of corresponding clutches of the freewheel type (not illustrated in detail as of known type) which enable free rotation of the pulleys 110, 120 with respect to the relative shafts in the advancement direction, while maintaining the constraint in the opposite direction; the reasons for this constructional detail will become evident in the following description.

The operative branches 11A, 12A of the belts 11, 12 are subjected to the action of respective stretcher rollers 112, 122 which guarantee contact with the vertical sides V of the pack C.

The stretcher rollers 112, 122 used are advantageously of the elastically oscillating type, with use of relative elastic means 113, 123.

The drive pulleys 110, 120 are synchronously activated in opposite directions, such that the operative branches 11A, 12A have an advancement direction W1 which is the same and a velocity which is at least equal to that of the conveyor line T.

The inlet group 10, with the respective initial part, is partially “superposed” on the terminal part of the conveyor line T.

The means 2 further comprise small connecting planes 13, 14, respectively situated upstream and downstream of the belts 11, 12 of the inlet group 10, destined to facilitate the entrance and exit of the pack C into and out of the inlet group 10 (FIG. 3).

The means 2 further comprise upper conveyor straps 21 and lower conveyor straps 22, destined to cooperate with the inlet group 10 and respectively for encountering the upper horizontal side Os and the lower horizontal side Oi of the pack C (FIGS. 4, 5); the straps 21, 22 are activated in synchrony by motor means, not illustrated, such that the operative branches thereof have a like advancement direction W2, and also a same direction as the advancement direction W1 of the inlet group 10.

The upper straps 21 exhibit an initial part in a suitably advanced position with respect to the position of the belts 11, 12, such as to enable exit of the drawing paddles Td of the conveyor line T, as described in more detail herein below (see in particular FIG. 4).

Two batteries 3, 4 of heat-welding idle rollers 30, 40 are located downstream of the inlet group 10, which batteries 3, 4 are symmetrically opposite one another and are reciprocally distanced in the longitudinal tract in which the upper straps 21 and the lower straps 22 extend.

The heat-welding idle rollers 30, 40 of each battery 3, 4 are arranged with the relative vertical axes mutually flanked and destined to intercept, in succession, the corresponding longitudinal vertical side V of the pack C, including the superposing strip S of the flaps Ls, Li, in order to heat the flaps Ls, Li up to a temperature which is sufficient to cause joining thereof by aggregation of the material thereof.

Each of the rollers 30, 40 is borne by respective tilting support means 31, 41, constituted, for example, by a right-angled lever, centrally hinged at a vertex thereof, with an arm bearing at an end thereof the roller 30, 40 and the other arm subjected to the action of elastic means 32, 42, which enable the roller 30, 40 to press elastically on the flaps Ls, Li in a transversal direction to the pack C, in consequence of the intercepting of the longitudinal vertical arm V.

As can be seen from FIGS. 3 and 6, the elastic oscillation of each roller 30, 40 is independent of the oscillation of the other rollers.

The rollers 30, 40 are heated and maintained constantly at a predetermined temperature (by way of example between 200° C. and 300° C.), by heating means associated to each of the rollers 30, 40.

The heating means, in a first possible embodiment denoted by references 130, 140, are of a hot-air type and comprise a semicircular casing 131, 141 destined to partially circumscribe the roller 30, 40 and at least an input conduit 132, 142 of hot air which opens in the space between the casing 131, 141 and the lateral surface of the roller 30, 40.

The hot air strikes the roller 30, 40 and heats it, and exits in the zone in which the roller enters into contact with the corresponding vertical side V of the pack C, also heating the plastic material of the wrapping, such as to facilitate heat- welding thereof (FIG. 9A).

The heating means, in a second possible embodiment, denoted by references 230, 240, are of a mixed type, with electrical resistances and hot air, and are housed internally of each roller 30, 40 (FIGS. 9B, 10).

Each roller 30, 40 is constituted by a fixed shaft 30A, 40A, associated to respective tilting support means 31, 41, on which, by means of interposing bearings 30B, 40B (for example ball bearings), an external roller surface 30C, 40C is rotatably borne, which external roller surface 30C, 40C is provided with a plurality of radial holes 30D, 40D.

The external roller surface 30C, 40C is partially covered by a semicircular casing 231, 241, similarly to what is described herein above.

The fixed shaft 30A, 40A is axially holed and is destined to house an electrical resistance 232, 242, for example a coil.

The electrical resistance 232, 242 is controlled by an appropriate heat probe of known type and not illustrated.

The central portion of the fixed shaft 30A, 40A bears a longitudinal flat section 30E, 40E, along which radial holes 30F, 40F are afforded which are destined to place the inside of the fixed shaft 30A, 40A in communication with an annular chamber 30G, 40G identified between the fixed shaft 30A, 40A and the external roller surface 30C, 40C.

Air is made to flow via an inlet conduit 233, 243 internally of the fixed shaft 30A, 40A, which air is heated by the electrical resistance 232, 242 and, via the radial holes 30F, 40F, reaches the annular chamber 30G, 40G; the hot air, together with the heat radiated by the electrical resistance 232, 242 raises the temperature of the external roller surface 30C, 40C.

The heated air further exits through the radial holes 30D, 40D of the external roller surface 30C, 40C and directed, also with the aid of the casing 231, 241 toward the contact zone between the roller 30, 40 and the plastic material of the wrapper, contributing to the rapid heating thereof, thus facilitating the heat-welding.

In a preferred embodiment, the lateral surface of the rollers 30, 40 is very rough, in order to improve cohesion of the material of the wrapping of the pack C, during heat-welding, thus optimizing the welding operation.

The roughness can be obtained, for example, by milling (see FIG. 7).

The rollers 30, 40 are preferably made of metal and the lateral surface thereof can be clad with a layer of another material, for example Teflon, ceramic or another still.

Cooling means 5 are comprised downstream of the batteries 3, 4 of rollers 30, 40, which cooling means 5 are destined to act on the flaps Ls, Li heat-welded by the rollers 30, 40 in order to lower the temperature thereof and stabilize the join.

The cooling means 5, of substantially known type, are constituted by plates 50, preferably sprung, which are internally interested by the circulation (not illustrated) of a cooling fluid.

The means of the device 1 described up to now are borne by relative support frames, not illustrated, with interposing of regulating means, also not illustrated, for calibrating the respective work positions, according to the format of the pack C.

In particular, with reference to the width of the pack C, the following are regulated:

-   -   the free space between the conveyor belts 11, 12 of the inlet         group 10, in relation to the positions of the relative         connecting planes 13, 14;     -   the free space between the batteries 3, 4 of heat-welding         rollers 30, 40, such as to define the interference with the         longitudinal vertical sides V and thus the pressure elastically         exerted by each roller on the flaps Ls, Li from which a dynamic         deformation of the pack C in transit derives, which increases         the contact surface with the corresponding roller 30, 40 (see         FIG. 7);     -   the free space between the cooling plates 50;     -   the transversal interaxis between the upper straps 21 and,         correspondingly, the lower flaps 22 (see FIG. 5).

The variation in the height of the pack C leads only to a matching of the level of the upper straps 21, as all the other described means exhibit a height development calibrated such as to be suited to the range comprised between the minimum and the maximum of the pack C.

The functioning of the device 1 will now be described, with the belts 11, 12 of the inlet group 10 and the upper straps 21 and the lower straps 22 activated at a same speed as that of the conveyor line T, and with the rollers 30, 40 heated to working temperature.

The pack C, conveyed by the relative drawing paddles Td of the conveyor line T, enters the belts 11, 12 of the inlet group 10 which are travelling at the same velocity (position C* in a dotted line of FIG. 4).

When the paddles Td begin to follow the circular trajectory about the return pulley of the conveyor line T they impress a transitory acceleration on the pack C and a consequent increase in velocity, which is accepted undraggingly by the belts 11, 12 due to the presence of the freewheel clutch on the drive pulleys 110, 120 (positions C**, broken line in FIG. 4).

The pack C thus enters into the grip of the upper straps 21 and lower straps 22 and is conveyed such as to transit between the batteries 3, 4 of heat-welding rollers 30, 40 where, as previously described, they are joined to the superposed flaps Ls, Li.

Immediately downstream, the cooling plates 50 stabilize the just-completed heat-welding.

In a first constructional variant of the device 1 the batteries 3, 4 are constituted by motorized heat-welding rollers 30M, 40M, destined to advance the pack C, downstream of the inlet group 10, in place of the upper straps 21 and the lower straps 22; the horizontal support of the pack C is given, for example, by a low-friction sliding plane, not illustrated.

Some of the motorized heat-welding rollers 30M, 40M and the relative flexible transmission means 35, 45 with which the rollers 30M, 40M are synchronously activated in the same direction are schematically illustrated in FIG. 8.

In the first variant, the means 2 for receiving and moving the packs C comprise, apart from the inlet group 10 with the relative connecting planes 13, 14, the motorized heat-welding rollers 30M, 40M, and the sliding plane.

A second constructional variant of the device 1, derived from the first and not illustrated, comprises a certain number of motorized rollers, arranged such as to precede the motorized heat-welding rollers 30M, 40M of the batteries 3, 4 to define the inlet group 10 in place of the belts 11, 12.

Each of the motorized rollers is borne with a vertical axis by tilting support means which are identical to the ones described herein above, and is keyed on the relative drawing gear with an interposing of a freewheel clutch, such as to have the same functional characteristics as described with reference to the belts 11, 12 in the transitory increase of velocity of the pack C.

The motorized heat-welding rollers 30M, 40M are also provided with heating means, for example such as those previously described with reference to the idle rollers 30, 40.

In this case too, the resting of the pack C is given by a low-friction sliding plane.

In the second variant, the means 2 for receiving and the movement of the packs C comprise the motorized rollers at the inlet, the motorized heat-welding rollers 30M, 40M, the sliding plane, as well as suitable connecting planes.

From the above description the special characteristics of the present device clearly emerge, especially in offering an optimal functioning for long time periods with the frequent and expensive maintenance operations with afflict the devices of the known art.

The device, as described herein, can be considered universal, as it can advantageously be interfaced with all types of packing machines without any need for modification.

Among the constructional solutions adopted for the device, it is important to make a special mentioned of the freewheel clutches, which do not generate dragging while aiding the transitory acceleration impressed on the packs by the conveyor system of the packing machine.

The described device, thanks to its simple conception, is particularly reliable during functioning and is able to optimally realize, with the roller batteries, the heat-welding of the flaps.

A further and not final positive note relates to the economic aspect, which delivers production costs that are certainly comparable to those of the prior-art solutions, but which enable considerable savings in management and maintenance costs, as specified.

The foregoing is intended by way of non-limiting example, and any modifications to details of the invention which might become necessary for technical and/or functional reasons, are considered to fall within the ambit of protection defined by the following claims. 

1. A device for heat-welding superposed flaps of a wrapping enveloping a pack of articles, for associating downstream of a packing machine in which the pack (C) of articles is formed, the flaps being arranged at longitudinal vertical sides (V) thereof, and folded in a predetermined order such that an upper flap (Ls) is external of and superposed on a lower flap (Li) and a superposing strip (S) develops horizontally, the device comprising: two batteries (3, 4) of heat-welding rollers (30, 40) symmetrically opposite one another, the rollers (30, 40) of each battery (3, 4) being arranged with relative axes thereof disposed vertically, the two batteries (3, 4) being mutually flanked and destined to intercept in succession a corresponding longitudinal vertical side (V) of the pack (C), also including the strip (S) for superposing on the flaps (Ls, Li) in order to heat the flaps (Ls, Li) up to a temperature which is sufficient to cause joining thereof by aggregation of a material of which the flaps (Ls, Li) and the strip (S) are made; tilting support means (31, 41) associated to each of the rollers (30, 40) and enabling each of the rollers (30, 40) to press elastically on the flaps (Ls, Li) in a transversal direction to the pack (C), consequently to intercepting of the longitudinal vertical side (V) and independently of the other rollers (30, 40); cooling means (5) arranged downstream of the batteries (3, 4) of rollers for acting on the flaps (Ls, Li) which have been superposed and heat- welded by the batteries (3, 4) of rollers, which cooling means (5) lower a temperature of the flaps (3, 4) and stabilize the joining thereof; means (2) for receiving the packs (C), at an end of a conveyor line (T) comprised in the packing machine, the means (2) for receiving also moving the packs (C) downstream of the packing machine, in a same direction, same orientation and with a velocity which is at least equal to a velocity of the conveyor line (T), for a tract of a length which enables the packs (C) to transit first to the batteries (3, 4) of heat-welding rollers and then to the cooling means (5).
 2. The device of claim 1, wherein the heat-welding rollers (30, 40) are borne idle on the respective tilting support means (31, 41).
 3. The device of claim 1, wherein the heat-welding rollers (30, 40) exhibit a lateral surface having a high degree of roughness.
 4. The device of claim 1, wherein the tilting support means (31, 41) are constituted by a right-angled lever, centrally articulated at a vertex thereof, with an arm thereof bearing the relative roller (30, 40) and with a remaining arm thereof subjected to an action of elastic means (32, 42) included for enabling the roller (30, 40) to press elastically on the flaps (Ls, Li), in a transversal direction to the pack (C), consequently to the intercepting of the longitudinal vertical side (V).
 5. The device of claim 1, further comprising heating means (130, 140, 230, 240) provided for the heat-welding rollers (30, 40) and for maintaining the heat-welding rollers (30, 40) at a predetermined temperature.
 6. The device of claim 5, wherein the heating means (130, 140) operate with hot air and comprise a semicircular casing (131, 141), designed to partially circumscribe the relative roller (30, 40) and at least an input conduit (132, 142) of hot air, opening into a space existing between the casing (131, 141) and the lateral surface of the roller (30, 40), the hot air being destined to strike and heat the roller (30, 40), as well as exiting from a zone in which the roller (30, 40) enters into contact with the corresponding vertical side (V) of the pack (C), and thus further heating the plastic material of the wrapping.
 7. The device of claim 5, wherein the heating means (230, 240) exhibit an electrical resistance and operate with hot air and comprise: a semicircular casing (231, 241) designed to partially circumscribe the relative roller (30, 40), the roller (30, 40) being constituted by a fixed shaft (30A, 40A) on which an external surface (30C, 40C) is rotatably borne, the external surface (30C, 40C) being provided with a plurality of radial holes (30D, 40D); at least an electrical resistance (232, 242) housed internally of an axial hole provided in the fixed shaft (30A, 40A); an input conduit (233, 243) destined to enable air to flow internally of the axial hole of the fixed shaft (30A, 40A), which air is destined to be heated by the electrical resistance (232, 242); radial holes (30F, 40F), provided in the central portion of the fixed shaft (30A, 40A), which radial holes (30F, 40F) place the axial hole of the fixed shaft (30A, 40A) in communication with an annular chamber (30G, 40G) identified between the fixed shaft (30A, 40A) and the external surface (30C, 40C), the hot air together with the heat radiated by the electrical resistance (232, 242) heating the external surface (30C, 40C) as well as to exit through the radial holes (30D, 40D) present therein, in order to further heat the plastic material of the wrapping.
 8. The device of claim 7, wherein a longitudinal flat portion (30F, 40F) is located in a central portion of the fixed shaft (30A, 40A), at the position of the radial holes (30F, 40F).
 9. The device of claim 1, wherein the means (2) for receiving and moving the packs (C) comprise: an inlet group (10) for intercepting the longitudinal vertical sides (V) of the packs (C), in outlet from the conveyor line (T) upstream of the batteries (3, 4) of rollers; clutch means, associated to the inlet group (10), destined to aid a transitory increase in velocity of the packs (C) on outlet from the conveyor line (T); connecting planes (13, 14) respectively situated upstream and downstream of the inlet group (10), destined to facilitate entry and exit of the pack (C) into and out of the inlet group (10); upper conveyor straps (21) and lower conveyor straps (22), respectively included for contactingly receiving the horizontal upper side (Os) and the horizontal lower side (Oi) of the pack (C), extending downstream of the inlet group (10) and being destined to cooperate with the inlet group (10) for advancing the pack (C).
 10. The device of claim 1, wherein the means (2) for receiving and moving the packs (C) comprise: an inlet group (10), destined to intercept the longitudinal vertical sides (V) of the packs (C) in outlet from the conveyor line (T), and located before the batteries (3, 4) of rollers; clutch means, associated to the inlet group (10), destined to aid transitory increases in velocity of the packs (C) on outlet from the conveyor line (T); connecting planes (13, 14), respectively situated upstream and downstream of the inlet group (10), destined to facilitate entry and exit of the packs (C) into and out of the inlet group (10); powered heat-welding rollers (30M, 40M) included in the batteries (3, 4) destined to cooperate with the inlet group (10) for advancing the pack (C); a sliding plane for horizontally supporting the pack (C).
 11. The device of claim 9, wherein the inlet group (10) is constituted by a pair of conveyor belts (11, 12) arranged symmetrically, each of which is ring-wound and stretched about corresponding pairs of pulleys, respectively a drive pulley (110, 120) and a driven pulley (111, 121) having relative vertical axes, the clutch means having freewheel mechanisms, interposed between the drive pulleys (110, 120) and the respective shafts, for enabling free rotation of the drive pulleys (110, 120) with respect to the shafts in the advancement direction, while maintaining the constraint in the opposite direction.
 12. The device of claim 11, wherein operative branches (11A, 12A) of the belts (11, 12) are subjected to action of the respective stretcher rollers (112, 122) which ensure contact with the vertical sides (V) of the pack (C).
 13. The device of claim 10, wherein the inlet group (10) is constituted by two series of drive rollers, arranged symmetrically, with the rollers borne with a vertical axis by relative tilting support means, and in that the clutch means have freewheel mechanisms, interposed between each of the drive rollers and the relative drawing gear, for enabling free rotation of the drive roller with respect thereto in the advancement direction, while maintaining the constraint in the opposite direction.
 14. The device of claim 10 wherein the inlet group (10) is constituted by a pair of conveyor belts (11, 12) arranged symmetrically, each of which is ring-wound and stretched about corresponding pairs of pulleys, respectively a drive pulley (110, 120) and a driven pulley (111, 121) having relative vertical axes, the clutch means having freewheel mechanisms, interposed between the drive pulleys (110, 120) and the respective shafts, for enabling free rotation of the drive pulleys (110, 120) with respect to the shafts in the advancement direction, while maintaining the constraint in the opposite direction.
 15. The device of claim 14, wherein operative branches (11A, 12A) of the belts (11, 12) are subjected to action of the respective stretcher rollers (112, 122) which ensure contact with the vertical sides (V) of the pack (C). 